3 Electron Transfer ReactionsElectron transfer reactions are oxidation-reduction or redox reactions.Redox reactions can result in the generation of an electric current or be caused by imposing an electric current.Therefore, this field of chemistry is often called ELECTROCHEMISTRY.

4 Why Study Electrochemistry?BatteriesCorrosionIndustrial production of chemicals such as Cl2, NaOH, F2 and AlBiological redox reactionsThe heme group

5 Review of Terminology for Redox ReactionsOXIDATION—loss of electron(s) by a species; increase in oxidation number.REDUCTION—gain of electron(s); decrease in oxidation number.OXIDIZING AGENT—electron acceptor; species is reduced.REDUCING AGENT—electron donor; species is oxidized.

17 Add H2O on O-deficient side and add H+ on other side for H-balance.Balancing EquationsBalance the following in acid solution—VO Zn ---> VO Zn2+Step 1: Write the half-reactionsOx Zn ---> Zn2+Red VO > VO2+Step 2: Balance each half-reaction for mass.Red2 H+ +VO > VO H2OAdd H2O on O-deficient side and add H+ on other side for H-balance.

19 Tips on Balancing EquationsNever add O2, O atoms, or O2- to balance oxygen.Never add H2 or H atoms to balance hydrogen.Be sure to write the correct charges on all the ions.Check your work at the end to make sure mass and charge are balanced.PRACTICE!